It's happening again. The "inevitability" of Hillary Clinton's presidential candidacy may not be so inevitable after all. Unlike eight years ago when Barack Obama beat her for the Democratic nomination and ultimately won the office Hillary and her supporters believed she was entitled to, this time her main opponent is not just Sen. Bernie Sanders, a socialist, it is Hillary Clinton herself.

Serious media and congressional investigations into Richard Nixon's Watergate crimes did not begin until after his landslide win in 1972. In Hillary Clinton's case, damaging investigations are occurring in the middle of her campaign.

Catherine Herridge, chief intelligence correspondent for the Fox News Channel, reports: "The FBI investigation into Hillary Clinton's use of private email as secretary of state has expanded to look at whether the possible 'intersection' of Clinton Foundation work and State Department business may have violated public corruption laws, three intelligence sources not authorized to speak on the record told Fox News. This track is in addition to the focus on classified material found on Clinton's personal server."

As Investors.com notes, "Hillary Clinton's support among Democrats nationally has taken a serious tumble, falling eight points to 43 percent, according to the latest IBD/TIPP Poll. Support for her chief rival, Bernie Sanders, rose six points to 39 percent. As a result, Clinton's lead over Sanders, which had been 18 points, is now just four points."

According to the latest NBC News/Wall Street Journal/Marist College poll, Clinton and Sanders are in tight races in both Iowa and New Hampshire. With less than three weeks before the Iowa caucuses, such numbers are not good news for any candidate, especially Hillary Clinton, whose veracity and job record in the various offices and positions she has held are anything but stellar. Very quickly, Clinton has gone from big mo, to slow mo, to no mo.

Americans wisely don't fully trust politicians of either party, but Hillary Clinton suffers more than most. Last August, a Quinnipiac University poll found that only 34 percent of those Americans surveyed believed Clinton is "honest and trustworthy." Peter A. Brown, assistant director of the poll, reports CNN.com, said that Clinton is experiencing a "continuing slide" with how she is "perceived by voters who continue to say she is not honest and trustworthy."

Democrats are likely worried not just about whether Clinton can capture the nomination -- and the odds still favor that outcome -- but whether she will be further damaged by the FBI investigations and whether that damage could possibly lead to an indictment, as some Republicans hope. Donald Trump has added to Clinton's woes by bringing up her husband's past behavior toward women at a time when she has positioned herself as the women's champion.

Voices are being heard among the political classes about the possibility of replacing Clinton on the Democratic ticket with Vice President Joe Biden should that become necessary. Such a move could severely impair the Democrat's ability to win the female vote. In a highly unpredictable political year, the Biden scenario would take unpredictability to a new level.

I saw a bumper sticker recently that proclaimed the driver was "Ready for Hillary." With the candidate's disapproval numbers rising and her approval numbers slip slidin' away, it doesn't appear that too many other voters are, in fact, ready.